1 //===- MemDerefPrinter.cpp - Printer for isDereferenceablePointer ---------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/Analysis/Loads.h"
11 #include "llvm/Analysis/Passes.h"
12 #include "llvm/IR/CallSite.h"
13 #include "llvm/IR/DataLayout.h"
14 #include "llvm/IR/InstIterator.h"
15 #include "llvm/IR/LLVMContext.h"
16 #include "llvm/IR/Module.h"
17 #include "llvm/Support/ErrorHandling.h"
18 #include "llvm/Support/raw_ostream.h"
19 using namespace llvm;
20 
21 namespace {
22   struct MemDerefPrinter : public FunctionPass {
23     SmallVector<Value *, 4> Deref;
24     SmallPtrSet<Value *, 4> DerefAndAligned;
25 
26     static char ID; // Pass identification, replacement for typeid
27     MemDerefPrinter() : FunctionPass(ID) {
28       initializeMemDerefPrinterPass(*PassRegistry::getPassRegistry());
29     }
30     void getAnalysisUsage(AnalysisUsage &AU) const override {
31       AU.setPreservesAll();
32     }
33     bool runOnFunction(Function &F) override;
34     void print(raw_ostream &OS, const Module * = nullptr) const override;
35     void releaseMemory() override {
36       Deref.clear();
37       DerefAndAligned.clear();
38     }
39   };
40 }
41 
42 char MemDerefPrinter::ID = 0;
43 INITIALIZE_PASS_BEGIN(MemDerefPrinter, "print-memderefs",
44                       "Memory Dereferenciblity of pointers in function", false, true)
45 INITIALIZE_PASS_END(MemDerefPrinter, "print-memderefs",
46                     "Memory Dereferenciblity of pointers in function", false, true)
47 
48 FunctionPass *llvm::createMemDerefPrinter() {
49   return new MemDerefPrinter();
50 }
51 
52 bool MemDerefPrinter::runOnFunction(Function &F) {
53   const DataLayout &DL = F.getParent()->getDataLayout();
54   for (auto &I: instructions(F)) {
55     if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
56       Value *PO = LI->getPointerOperand();
57       if (isDereferenceablePointer(PO, DL))
58         Deref.push_back(PO);
59       if (isDereferenceableAndAlignedPointer(PO, LI->getAlignment(), DL))
60         DerefAndAligned.insert(PO);
61     }
62   }
63   return false;
64 }
65 
66 void MemDerefPrinter::print(raw_ostream &OS, const Module *M) const {
67   OS << "The following are dereferenceable:\n";
68   for (Value *V: Deref) {
69     V->print(OS);
70     if (DerefAndAligned.count(V))
71       OS << "\t(aligned)";
72     else
73       OS << "\t(unaligned)";
74     OS << "\n\n";
75   }
76 }
77